Hi Folks,
ENGLISH SENTENCES
Compare these two sentences:
Say your name out loud.
Say "your name" out loud.
By wrapping those two words in quotes they are broken out of their normal meaning. They lose all meaning and just become syntactic/meaningless entities. We could just as well have said:
Say "blipity do" out loud.
This illustrates the use/mention distinction in natural language semantics. The unquoted is used, the quoted is mentioned. If you would like to read more about this, see http://plato.stanford.edu/entries/quotation/.
XML MARKUP
Compare these:
<Book>
&lt;Book>
By escaping the less-than symbol it is broken out of its normal meaning. An XML parser will no longer treat it as signifying the start of an element; it will simply treat it as a meaningless character, along with the following characters.
REGULAR EXPRESSIONS
XML Schema, XSLT 2.0, Schematron, and HTML5 use regular expressions.
In the regular expression language, the dash symbol is a special character that means range. This regular expression says any digit from zero to nine:
[0-9]
By preceding the dash with a backslash:
[0\-9]
we have broken the dash out of its normal meaning and it just becomes a meaningless character. The regex now says zero, dash, or nine.
RECURRING PATTERN
Above I presented three examples of breaking out of normal interpretation/meaning. This suggests that breaking out of normal interpretation/meaning is a recurring pattern.
/Roger